import matplotlib.pyplot as plt
import numpy as np
def Sigmoid(x):
    return 1./(1.+np.exp(-x))
x=np.arange(-20,20,0.5)
y=Sigmoid(x)
plt.plot(x,y)
plt.show()

import matplotlib.pyplot as plt
import numpy as np
def ReLU(x):
    return(np.abs(x)+x)/2.0
x=np.arange(-20,20,0.5)
y=ReLU(x)
plt.plot(x,y)
plt.show()